The task of making cast-in components during the production of metal castings has challenged manufacturers since the earliest days of automotive manufacturing. For example, this challenge is particularly great in the manufacture of engine blocks having cast-in cylinder liners. Over time, manufacturers found that pre-heating the cast-in component resulted in a superior product.
The previous solutions to pre-heating cast-in components include both induction heating (when manufactured in high volumes) and designing a mold package in which the molten material is in direct contact with the cylinder liner. A dual runner (or riser) system is formed into the casting mold assembly. During the primary pour, the molten metal flows past the cast-in component in an attempt to heat it. In this way, the molten metal used to heat the liners is in direct contact with the insert.
However, when used in direct contact with the liner insert, there is little control of the heating time, the position of the molten metal, or the temperature profile of the insert. Particularly, the same metal that is trying to heat the component is also the metal that the manufacturer desires to stay at the pour temperature so that a quality casting is made. However, the act of heating the cast-in component cools the molten metal and may prematurely solidify it.
Additionally, that material solidifies and adheres to the insert requiring additional machining processes to remove. Depending on the shape of the insert, it may also not be possible to completely remove the heating material from the insert.
In summary, finding an economical and practical method of pre-heating cast-in inserts during manufacturing is a problem that remained unsolved until the present invention.